Coupling adapter



FIG. 1 is a perspective view of a coupling adapter of the present design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a front elevation view thereof, the rear elevation view being identical;

FIG. 4 is a side elevation view thereof, the other side elevation view being identical;

FIG. 5 is a top plan view thereof;

FIG. 6 is a perspective view shown in an environment of use thereof; and,

FIG. 7 is a perspective view thereof shown in a second environment of use. 

CLAIM The ornamental design for a coupling adapter, as shown and described. 